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Space Elevator

neal.fun

81–90 of 216 posts

Re: Space Elevator

#81

FYI, this crashed my browser with extreme prejudice; I can't remember one other time when I've had to force-stop the application. (Firefox on Android)

Sounds like another good reason to move on from Mozilla.

That would require a reasonable alternative.

Re: Space Elevator

#82
post #58

Earlier quoted context omitted.

For a ring with a density of 10kg/m, that kinetic energy is about 5 megatons… spread over 40,000km. It's negligible when it's that diffuse. Even if it didn't burn up, it's mostly lost to air resistance, with everything over a few hundred meters being limited to about terminal velocity. And that size ring, is pretty useful.

https://www.wired.com/story/what-happens-if-a-space-elevator...

That fails to illuminate very much.

Also, ring != elevator.

Probably still want to engineer it such that destruction is controlled rather than uncontrollable, but the biggest issue with it being destroyed would be no longer having it; the damage would be mostly within a meter or so of where it lands, which isn't great but it's also not devastating unless you happen to be that close.

Think a very long I-beam falling off a skyscraper during construction, not an asteroid.

Re: Space Elevator

#84

I love this. Reminds me of a thread I perused once re Orbital Ring Space elevator concept, and how it seems not only possible, but almost disgustingly cheap (in terms of the gains) with current technology. Not only would such an endeavor restore some aspect of pride to humanity, but the benefits are quite numerous. To name a few low-hanging fruit: The research done to make it possible, would definitely advance severa…

Never mind space elevators - we could build useful sky hooks right now (and Mars might be the best place to do it...) https://youtu.be/dqwpQarrDwk

Re: Space Elevator

#85

This is great. I just wish there was one way to switch all units. The temp. can be switched between F/C by tapping on it. The height is metric and seems fixed and then stuff in text bubbles is again imperial (e.g. mph instead of kph).

That is mostly because the international space community works with metric, so the Karman line is at 100km above earth, and converting to imperial units would be forced. Remember, there are only three countries that use imperial units; two third-world counties, and a global superpower.

That’s not entirely true. The UK and Australia use Imperial measurements quite frequently, especially for speed.

Re: Space Elevator

#86

This was great! Niggle: With a trackpad, you might need to scroll "down." I thought it wasn't working, for a few seconds, but that's a fairly common issue with trackpads and mobile interfaces. "Up" and "down" are kind of relative.

Not with mine. You have your trackpad set reverse to mine which is default in some systems because kids expect it to work more like a smartphone/tablet rather than a scroll wheel.

I just have it at Apple default. It is the same as scrolling windows, but "up" is interpreted differently, in my brain (not a kid. I'm an old fart).

Re: Space Elevator

#87
post #62

Couple of things I learned from this: 1. Some birds go really high into the sky. Not sure how they evolved to tolerate such a hostile environment. But it seems that Duck-like birds are able to handle very high altitude. 2. There are lots of cool spaceships that man has made. But it seems most of these were made in the 1950-1990 era. It's a shame that we are no longer doing that.

I have to wonder what you mean we're no longer making cool spacecraft? The SpaceX starship is about to launch in an hour, it's very cool.

Watching the countdown now! T-00:28:12! Will be spectacular no matter what happens! Yes, I'm excited. Not sure how the parent comment has missed what SpaceX has been doing with Dragon, Starship, Starlink, and all the rockets! Amazing.

Re: Space Elevator

#88
"Above this altitude is known as the 'death zone', because there isn't enough oxygen for human life."

whooper swan casually floats by

Re: Space Elevator

#89

At 74km/h you would reach space (100km karman line) in an hour and a half but you would need to keep going for another 20 days at that speed reach geostationary orbit in order to not fall back to earth when you exit the space elevator.

At that point gravity will act slower though, so it might be enough to take up a small liquid fuel craft too. Rockets will have abandoned solid fuel boosters long before then.

If you take a lift to a distance of 100 km and drop it, it will fall immediately reaching the ground in less than 10 minutes. Gravity remains strong.

Satellites and space stations are always in free fall. The thing that keeps them in "space" is the velocity with which they were originally launched to orbit the Earth as centripetal force becomes the weight of the satellite, which slows down such falling process. Seeing it with cold eyes, they employ all the energy at a first for to lift the weight of that falling object.

If a geostationary satellite has to stay over the same region of the planet, it has to be sent much much far away, until its orbital velocity become synchronized with the Earth's rotation. And even like that, keeps being in free fall due Earth's gravity.

I mean, what we see in cartoons or sci-movies about to send a rocket absolutely vertical and cut engines, or a spaceship joining over a planet and conserve the same orbital position, could be done only with anti-gravitational engines. A small liquid fuel could not maintain them in place.

Re: Space Elevator

#90

Earlier quoted context omitted.

My understanding is that it would be under tension and orbiting at beyond escape velocity, such that if it got cut off, it would fly away from Earth. Still bad, but not catastrophically. Maybe we could even recover it.

That all assumes that it got loose at the base and not part way up within the atmosphere. If 9/11 can happen, this can happen. All that cable and kinetic energy has to go somewhere.

If your bad guys can get high enough to sever your cable, they can get high enough to do a kinetic or powered bombardment and cause magnitudes more damage.
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